Ignition system



June 25, 1935. D, S|| VERMAN 2,005,875

IGNITION SYSTEM ,Filed Feb. 14, 1934 JZ i Dan/'e/ /rermon,

ai ,JM www ATTORN EY .Patented June 25, 1935l IGNITION SYSTEM Daniel Silverman, Wilkinsburg, Pn., assigner te Westinghouse Electric & Manufacturing Company,.East Pittsburgh, Pag, a corporation of Pennsylvania Application February 14,1934, sei-inl No. 111,192

(cl. ris-.363)

12 Claims.

My invention relates to vapor electric converters and particularly to an ignition system for such devices.

In the application ofvapor-electric devices employing a make-alive' type of excitation it is frequently desirableto operate a plurality of elements in parallel instead of constructing a single special unit for delivering a desired current rating.

In the construction of these devices, it has heretofore been customary to provide a complete ignition system for each unit of the converters. Each or these make alive systems employs a suitable auxiliary discharge device for controlling the flow of current to the make alive electrode.

When a plurality of devices are used in parallel, all of the make alives should be energized substantially simultaneously. Consequently,it is an object of my invention to providev a makealive system by which all the make alives are energized simultaneously. Since the auxiliary discharge devices, such as glow tubes, are of relatively short life, it follows thatthe major portion of the up-keep cost of the ignition system is in the replacement of these auxiliary tubes.v

It is a further object of my invention to re' duce the num'ber of these tubes in order to reduce the up-keep cost of make alive installations.

It is a further object of my invention to provide current dividing apparatus for insuring current ow to all 'of a plurality of parallel connected make alive electrodes.

It is a further object of my invention to provide means for substantially stoppingthe current flow in the make alive electrode. after it has established the arc in the main discharge device. Y

Other objects and advantages of my invention Will be apparent from the following detailed description taken in conjunction with the accompanying drawing, in which Figure 1 is a schematic illustration of a portion of a converter installation embodying my invention,

Fig. 2 is a similar view showing a further modiiication according tomy invention, and

Fig. 3 is a similar view of a similar embodiment of my invention. 1

I'he apparatus according to my invention comprises a suitable alternating current system such as an alternating current transformer I provided with a plurality of phase terminals 2, a direct current system having one side 3 thereof connected to the alternating current system and a. plurality of converters between each phase terminal 2 of the alternating current system I and one side 4 of the direct current line. g

Each of the converters 5 between the common phase terminal 2 and the alternating current line'3 are connected in parallel by means of suitable current dividing equipment such as anode balance coils 6. In each of the converters 5 is a suitable make alive electrode I for initiating a cathode spot at the beginning of each l0 current carrying half cycle.

These make alive electrodes I are connected in parallel by a suitable conductor 8 and supplied with current by' a suitable auxiliary valve I0 which is, in turn, supplied either from an aux- 15 iliary source II or from the phase terminal 2 to which the valves 5 are connected. When the potential applied to the anodes of the converter 5 is positive, the auxiliary valve IIJ will break down to permit Lcurrent flow to the parallel con- 20 current will divide equally between the various 30 parallel connected electrodes. In order to obviate this difficulty, I introduce a current dividing device between the electrodes and a common source of electrode current.

In the preferred embodiment of my invention, 35

I provide a suitable capacitor I5 in series with each of the make alive electrodes 'I `and when make alive potential is applied to the electrodes 'I, current starts to ow in each electrode 'l substantially equal to the charging current taken 40 by the several capacitors I5. Thi-s current continues to flow until a cathode spot is established at which time an arc will strike from the electrode holder to the cathode spot. This causes a'rush of current which rapidly charges the se- 45 ries capacitor I5 and so substantially interrupts current flow to that particular electrode. If lone of the parallel connected electrodes 'I should fail to create its cathode spot, the current from the excitation source will continue to flow to that 50 electrode and also the potential stored in the remaining capacitors I5 will be available for creating a cathode spot in the late firing unit. In

order to discharge the series capacitor I5, I prof vide a resistor I6 in shunt therewith. These re. 55

a suitable balancing transformer 20. When the positive potential is applied to the anode Vcircuit, the auxiliary valve l0 allows current to flow to the common connection 8 of the make alive electrodes l. Because of the relatively high inductance of the transformer winding 20, make alive current is carried substantially entirely by the series capacitors I5. As soon as one of the electrodes 'I has initiated a rectifying arc, current will flow through the main balancing reactor 6 of the active unit and-set up in itself a back voltage which increases the potential applied to the anode of the non-firing unit.

Closely associated with this main balance coil is the transformer winding 2D in the ignition circuit. By transformer action, the lcurrent to the active unit sets up a voltage in the coil which is positive with respect to the make alive electrode 'l of the non-firing unit. This increased potential is then effective to force suiiicient current through the make alive electrode I to initiate a cathode spot and consequently the main rectifying arc therein. As soon as both of the converter units carry current, the .potentials generated in the ignition transformerfz counter balance each other and the flowuf current to the make alive electrode 1 substantially ceases. The series capacitors A.l5 will then discharge through their respective sections of the ignition transgformer winding 20 so as to be in readiness for initiating a cathode spot on the succeeding halt cycle. s y

In a further modification of4 my invention, I use a current balancingreactor 25 to apply additional potential` to the electrode of a non-ring element. In this modification when the positive potential is applied to the ignition circuit through the auxiliary valve l0, current ilows primarily through the series capacitors to the make alive electrodes. However, after a short interval of time, current willilow through the parallel sections of the balancing reactor so that when the cathode spot has been initiated relatively heavy currents will flow through one half of the balancing reactor 25 to the electrode holder and from there to the cathode of the .active section. By mutual induction, this current produces a relatively high potential, which is applied to the electrode 'l of the non-iiring section to assist in initiating a cathode spot therein.

While for purposes of illustration, I have shown specific embodiments of my invention, it will be apparent to those skilled in the art that changes and -rnodications' can be made therein without departing from the true spirit of my invention o the scope of the appended claims.

I claim as my invention:

`1. A vapor-electric converter comprising i a source of polyphase currents, a load circuit, a plurality of parallel valves between each phase of the source and the load circuit, a make-alive electrode associated with each of said valves, said electrodes being connected in parallel, a source of excitation current substantially co-phasal with the polyphase source and means responsive to the polarity of the polyphase` source for connecting said excitation source to said electrodes and capacitors in series with each of said electrodes for controlling current ilow thereto.

2. A vapor-electric conversion system comprising a supply line, a load line, a plurality of Valves connected between common terminals on said lines, a balancing reactor for dividing the load current between said valves, a make-alive electrode in each of said valves, means for applying starting current to said electrodes, a second balancing reactor for directing current between said electrodes, said second balancing reactor being associated with said rst mentioned reactor so that failure of one of said.valves to pick up impresses a high potential on the make-alive in the inactive valve.

3. A vapor-electric conversion system comprising a supply line, a load line, a plurality of valves connected between common terminals on said lines, a balancing reactor for dividing the load current between said valves, a make-alive electrode in each of said valves, means for applying starting current to said electrodes, a second balancing reactor for dividing current between said electrodes, said second balancing reactor being associated with said rst mentioned reactor so that failure of one of said valves to pick up impresses a high potential on the make-alive'in the inactive valve and capacitors 'in series with said electrodes and in parallel with said secondv reactor.

4. An ignition system for a converter having a plurality of parallel valves comprising a makealive electrode in each valve, a source of current for said make-alives, means responsive to the voltages applied to said valve for connecting said source to said make-alive electrodes, a capacitor inseries with each of said electrodes and means for discharging said capacitors.

5. An ignition system for a plurality of parallel connected vapor-electric valves comprising a make-alive electrode in each of said valves, a capacitor in series with each of said electrodes, a common connection to all of said capacitors and means vfor applying potential to said common connections at the beginning of each -current carrying period.

6. A'n ignition system for a plurality of parallel connected Vapor-electric valves comprising a make-*alive electrode in each of said valves, a capacitor in series with each of said electrodes, a common connection to all of said capacitors and lmeans for applying potential to said common connection at the beginning of each current carrying period and means in shunt with said capacitor for dissipating the energy stored there- 7. An ignition system for a vapor-electric converter having a plurality of parallel valves comprising an auxiliary electrode for initiating a cathode spot in the valve at the beginning of each conducting interval, a source of potential connected to the parallel valves, a source of potential for saidauxiliary electrodes, an auxiliary valve responsive to the polarity of the potential applied to the valve for controlling current ow to said auxiliary electrodes and a current divider for insuring current iiow to each of said auxiliary electrodes. l

8. An ignition system for a vapor-electric con- |verter having a plurality of parallel valves comprising an auxiliary electrode for'initiating a cathode spot in the valves at the beginning of each conducting interval, a source of potential 9. An electrical conversion system comprising an alternating current system, a direct current system, aplurality of vapor-electric converter units for transferring energy between said systems, a make-alive electrode in each of said units, said electrodes being connected in parallel, a source of current for said-make-alive electrodes, an electric valve for controlling current iiow to said electrodes and current balance means for insuring current flow to each of said electrodes.

10. An excitation system for a converter having a plurality of parallel valves comprising a make-alive electrode in each of said valves, an auxiliary valve for supplying current to all of said make-alive electrodes and a split reactor for aooasvs dividing current between said make-alive electrodes. l

11. An excitation system for a converter having a plurality of parallel valves comprising a make-alive electrode in each of said valves, an auxiliary valve for supplying v current to all of said make-alive electrodes and a split reactor for dividing current between said make-alive electrodes and a capacitor in shunt with each section of said reactor. 12. A vapor electric system comprising-a source of potential, 'a load system, a plurality of valves for simultaneously carrying current between said 'source and said system, a make-alive electrode associated with each of said valves, a source of current for said electrodes, means for simultaneously applying potential to said electrodes and.

means for interrupting current flow to said electrodes when the cathode spots'are initiated.

' DANIEL SILVERMAN. 

